Comparative Killing Efficiencies for Decays of Tritiated Compounds Incorporated into E. coli

The killing efficiencies due to the decay of incorporated H³-thymidine, H³-uridine, and H³-histidine in E. coli 15_T-L- have been determined. Decays from H³-thymidine are 2.0 times as effective in producing lethality as those from H³-uridine and 2.5 times as effective as those from H³-histidine. Therefore, it seems that the greater part of damage from H³-thymidine decays is due to chemical changes associated with nuclear transmutation.     

Differential Mutation Production by the Decay of Incorporated Tritium Compounds in Escherichia coli

We have studied the differential mutation production by the decay of incorporated tritium compounds in E. coli (WWU) using DNA-seeking precursors (H³-thymidine), RNA-seeking precursors (H³-uracil, H³-uridine), and protein-seeking precursors (H³-histidine, H³-proline). In particular we have determined the reversion frequency of an arginine locus. The reversion frequency is measured in units of revertants/surviving bacteria/H³ decay, and has an average value of 1.84 × 10^-8 for H³-uridine and H³-uracil, 0.67 × 10^-8 for H³-thymidine, and 0.28 × 10^-8 for H³-proline and H³-histidine. Thus, the revertants are produced most effectively by H³ decays when the label is introduced in the form of an RNA precursor. The macromolecular distribution of the label shows that 5 to 8 per cent of the H³-uridine or H³-uracil is incorporated into DNA.     

DNA SYNTHESIS IN THE OOPLASM OF DROSOPHILA MELANOGASTER

Tritiated thymidine was injected into 2-day-old Drosophila melanogaster females, and tissue sections were prepared from the ovary for radioautography with both the light and electron microscopes. Besides the expected incorporation of H³-thymidine into nuclei of nurse cells and follicle cells, there was a relatively high level of incorporation of label into ooplasmic DNA. The highest level of incorporation occurred at stage 12. At the same time, the 15 nurse cell nuclei also incorporate thymidine in spite of the fact that they are breaking down and degenerating. The label in the ooplasm is not removed by extraction with DNase (although this removes nuclear label) unless extraction is preceded by a treatment with protease. Electron microscopic radioautography revealed that 36% of the silver grains resulting from decay of H³-thymidine are found over mitochondria, with a further 28% being located within 0.25 µ of these organelles. The remaining 36% of the silver grains was not found to be associated with any organelles, and it probably represents synthesis in the cytoplasm by the "storage DNA" characteristic of many eggs. It is suggested that one mechanism acting throughout the egg chamber is responsible for the synchronous synthesis of DNA in the degenerating nurse cells, in the mitochondria of the egg, and in the "storage DNA" of the ooplasm.     

THYMIDINE DEGRADATION PRODUCTS IN PLANT TISSUES LABELED WITH TRITIATED THYMIDINE

A study of the metabolic pathways of H³-thymidine utilization in buds of Lilium longiflorum and root tips of Vicia faba was undertaken in order to obtain information that might explain the binding of H³ from H³-thymidine in the cytoplasm of these plants. H³-thymidine was administered for various periods of time, the tissues were fixed and processed in the manner routinely used in preparation for sectioning and autoradiography, and the radioactivity removed in this way from the tissues was determined. It was found that the ethanol/acetic acid fixative contained the major portion of the radioactivity. Analysis of this extract by paper chromatography showed that the radioactivity was distributed among various degradation products of thymidine, principally β-ureidoisobutyric acid and β-aminoisobutyric acid. Time course experiments with Vicia showed that these degradation products rapidly appeared in the tissue during incubation with H³-thymidine, while H³-thymine appeared in the incubation medium. Preliminary studies indicated that Vicia root tips incubated with H³-dihydrothymine for 24 hours would bind a small amount of H³ non-specifically in the cells. It seems unlikely that utilization of degradation products of H³-thymidine is sufficient to explain labeling which is concentrated in the cytoplasm.     

H3-THYMIDINE DERIVATIVE POOLS IN RELATION TO MACRONUCLEAR DNA SYNTHESIS IN TETRAHYMENA PYRIFORMIS

The formation of a soluble H³-thymidine derivative pool has been examined in Tetrahymena pyriformis as a function of macronuclear DNA synthesis during the cell life cycle. An autoradiographic technique which allows the detection of water-soluble materials within a cell has shown that these cells do not take up and retain exogenous H³-thymidine during G1 or G2. Uptake of H³-thymidine is restricted to the S period of the cell cycle. Additional autoradiographic experiments show, however, that a soluble pool of H³-thymidine derivatives persists from the end of one DNA synthesis period to the beginning of the next synthesis period in the subsequent cell cycle. Since this persisting pool cannot be labeled with H³-thymidine, the pool does not turn over during non-S periods.     

Hydrogen Sulfide Prolongs Postharvest Storage of Fresh-Cut Pears (Pyrus pyrifolia) by Alleviation of Oxidative Damage and Inhibition of Fungal Growth

Hydrogen sulfide (H₂S) has proved to be a multifunctional signaling molecule in plants and animals. Here, we investigated the role of H₂S in the decay of fresh-cut pears (Pyrus pyrifolia). H₂S gas released by sodium hydrosulfide (NaHS) prolonged the shelf life of fresh-cut pear slices in a dose-dependent manner. Moreover, H₂S maintained higher levels of reducing sugar and soluble protein in pear slices. H₂S significantly reduced the accumulation of hydrogen peroxide (H₂O₂), superoxide radicals (•O₂ ⁻) and malondialdehyde (MDA). Further investigation showed that H₂S fumigation up-regulated the activities of antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT), and guaiacol peroxidase (POD), while it down-regulated those of lipoxygenase (LOX), phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO). Furthermore, H₂S fumigation effectively inhibited the growth of two fungal pathogens of pear, Aspergillus niger and Penicillium expansum, suggesting that H₂S can be developed as an effective fungicide for postharvest storage. The present study implies that H₂S is involved in prolonging postharvest storage of pears by acting as an antioxidant and fungicide.     

Reversible sporicidal action of cuprous ions

At 10 mM, Cu⁺ was highly protective against killing of spores of Bacillus megaterium ATCC 19213 by H₂O₂, while at higher concentrations, from 15–100 mM, killing was augmented. In contrast, Cu²⁺, Fe²⁺, Fe³⁺, Co²⁺ or Co³⁺ ions acted only protectively. Cu⁺ itself was sporicidal in the absence of H₂O₂ or ascorbate, and its sporicidal action did not depend on generation of highly reactive oxygen species. It appeared that killing involved either inhibition of germination or copper toxicity to germinated cells in that Cu⁺-inactivated spores did not germinate readily but chemical decoating of the cells prior to plating on a solid medium resulted in reversal of the sporicidal effect. Received 12 July 1996/ Accepted in revised form 03 November 1996     

Microscopic and Thermal Characterization of Hydrogen Peroxide Killing and Lysis of Spores and Protection by Transition Metal Ions, Chelators, and Antioxidants

Killing of bacterial spores by H₂O₂ at elevated but sublethal temperatures and neutral pH occurred without lysis. However, with prolonged exposure or higher concentrations of the agent, secondary lytic processes caused major damage successively to the coat, cortex, and protoplast, as evidenced by electron and phase contrast microscopy. These processes were also reflected in changes in differential scanning calorimetric profiles for H₂O₂-treated spores. Endothermic transitions in the profiles occurred at lower temperatures than usual as a result of H₂O₂ damage. Thus, H₂O₂ sensitized the cells to heat damage. Longer exposure to H₂O₂ resulted in total disappearance of the transitions, indicative of major disruptions of cell structure. Spores but not vegetative cells were protected against the lethal action of H₂O₂ by the transition metal cations Cu⁺, Cu²⁺, Co²⁺, Co³⁺, Fe²⁺, Fe³⁺, Mn²⁺, Ti³⁺, and Ti⁴⁺. The metal chelator EDTA was also somewhat protective, while o-phenanthroline, citrate, deferoxamine, and ethanehydroxydiphosphonate were only marginally so. Superoxide dismutase and a variety of other free-radical scavengers were not protective. In contrast, reducing agents such as sulfhydryl compounds and ascorbate at concentrations of 20 to 50 mM were highly protective. Decoating or demineralization of the spores had only minor effects. The marked dependence of H₂O₂ sporicidal activity on moderately elevated temperature and the known low reactivity of H₂O₂ itself suggest that radicals are involved in its killing action. However, the protective effects of a variety of oxidized or reduced transition metal ions indicate that H₂O₂ killing of spores is markedly different from that of vegetative cells.     

Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.     

Magnetic and luminescence characteristics of dinuclear complexes of lanthanides and a phenolic schiff base macrocyclic ligand

The magnetic and luminescence characteristics of trimorphic homodinuclear macrocyclic complexes of lanthanides and a 2:2 phenolate Schiff's base L, derived from 2,6-diformyl-p-cresol and triethylenetetramine were determined. The complexes of Pr³⁺ exhibit non-Curie-Weiss temperature dependent magnetic susceptibilities for which satisfactory fits to an axial relationship depends on crystal field splitting and a weak binuclear Pr³⁺Pr³⁺ antiferromagnetic interaction. The exchange interaction parameters are zJ′ = −2.2, −4.4 and −7.0 cm ⁻¹ for ‘off-white’ Pr₂L(NO₃)₄·2H₂O, ‘yellow’ Pr₂L(NO₃)₄, and ‘orange’ Pr₂L(NO₃)₂(OH)₂, respectively. In contrast, magnetic susceptibilities of the Ln₂L(NO₃)₃(OH) complexes (Ln = Dy, Ho) follow Curie-Weiss behavior over the entire temperature range (6 K to 300 K). The complexes of closed shell ions La³⁺, Lu³⁺, Y³⁺ and those of the half filled shell ion Gd³⁺ exhibit a strong ligand fluorescence in the 450 nm to 650 nm range with decay times at 77 K of 5–8 ns for Ln≠Gd or 2–4 ns for Ln = Gd. The complexes of Gd³⁺ also exhibit a phosphorescence at 600 nm (decay time ∼ 200 μs). The complexes containing Ce³⁺, Eu³⁺, Tb³⁺ and Er³⁺ show very weak ligand luminescence indicative of effective quenching processes. Sensitized emission from the lanthanide ion is observed only with the Eu³⁺ complexes (⁵D_o → ⁷F_j transitions). The emission lifetimes are on the order of 250 μs in the pure Eu³⁺ complexes. The emission decay curves from dilute samples of Eu³⁺ in ‘off-white’ La₂L(NO₃)_4nH₂O show a noticeable rise time as well as a biphasic decay (fast component ∼ 400 μs; slow component ∼ 2500 μs). The luminescing states of L and Eu³⁺ have a common excitation spectrum which is similar to the electronic absorption spectrum of L indicating that ligand-to-metal ion energy transfer processes are dominant. Overall the result if this study suggest that the spectral properties of the complexes are determined by the coordination mode of the lanthanide ions to the Schiff base portion of macrocyclic ligand.     

Copper(II) complexes with unsymmetrical pentadentate ed3a-type diamino-tricarboxylate ligands. Crystal structures, configurational analysis and DFT study of complexes

The O-O-N-N-O-type pentadentate ligands H₃ed3a, H₃pd3a and H₃pd3p (H₃ed3a stands ethylenediamine-N,N,N′-triacetic acid; H₃pd3a stands 1,3-propanediamine-N,N,N′-triacetic acid and H₃pd3p stands 1,3-propanediamine-N,N,N′-tri-3-propionic acid) and the corresponding novel octahedral or square-planar/trigonal-bipyramidal copper(II) complexes have been prepared and characterized. H₃ed3a, H₃pd3a and H₃pd3p ligands coordinate to copper(II) ion via five donor atoms (three deprotonated carboxylate atoms and two amine nitrogens) affording octahedral in case of ed3a³⁻ and intermediate square-pyramidal/trigonal-bipyramidal structure in case of pd3a³⁻ and pd3p³⁻. A six coordinate, octahedral geometry has been established crystallographically for the [Mg(H₂O)₆][Cu(ed3a)(H₂O)]₂ · 2H₂O complex and five coordinate square-pyramidal for the [Mg(H₂O)₅Cu(pd3a)][Cu(pd3a)] · 2H₂O. Structural data correlating similar chelate Cu(II) complexes have been used for the better understanding the pathway: octahedral → square-pyramidal ↔ trigonal- bipyramid geometry. An extensive configuration analysis is discussed in relation to information obtained for similar complexes. The infra-red and electronic absorption spectra of the complexes are discussed in comparison with related complexes of known geometries. Molecular mechanics and density functional theory (DFT) programs have been used to model the most stable geometric isomer yielding, at the same time, significant structural data. The results from density functional studies have been compared with X-ray data.     

Carbonic acid as the host signal for the development of parasitic stages of nematodes

Petronijevic T., Rogers W. P. and Sommerville R. I. 1985. Carbonic acid as the host signal for the development of parasitic stages of nematodes. International Journal for Parasitology15: 661–667. This paper gives results on which may be based an identification of the component of the system CO₂ + H₂O ai H₂CO₃ ai H⁺ HCO₃^? which acts as the stimulus from the animal host for some nematodes. Using infective juveniles of Nematospiroides dubius and Haemonchus contortus, the effects on exsheathment of (1) low pCO₂ values, (2) the presence of carbonic anhydrase in the stimulating medium, and (3) the inhibition of carbonic anhydrase within the juveniles have been examined. The results lead to the suggestion that it is the “readily available” undissociated H₂CO₃, or H₂CO₃ + HCO₃^? which is the critical factor in the stimulus for development. The wide range of [H⁺]s over which “readily available” H₂CO₃ is present in physiological environments suggests that this host signal may be important for infection with many species.     

Structural, photophysical and electrochemical studies of [RuN6] complexes having polypyridine and azole mixed-donor sites

The mixed-ligand ruthenium(II) complexes [(phen)₂Ru(pzbzimH₃)](ClO₄)₂·3H₂O (1), [(phen)₂Ru(bzimH)₂](ClO₄)₂·3H₂O (2) and [(bpy)₂Ru(bpybzimH₂)](ClO₄)₂ (3), where phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine, pzbzimH₃ = pyrazole-3,5-bis(benzimidazole), bzimH = benzimidazole and bpybzimH₂ = 6,6′-bis(benzimidazole-2-yl)-2,2′-bipyridine have been synthesized and spectroscopically characterized. The X-ray structures of the three compounds have been determined which show that relative to the polypyridine ligands (phen or bpy) two donor nitrogens of the second ligand occupy cis position. In case of 3, bpybzimH₂ ligand is coordinated in puckered form where its bpy unit acts in a monodentate fashion. The electrochemical properties, absorption and emission spectral characteristics and lifetimes of luminescence decay of the complexes have been compared. Deprotonation of the azole NH moieties of the complexes lead to substantial lowering of redox potentials of the Ru^II/Ru^III couple as well as the MLCT and emission band energies. Spectrophotometric and spectrofluorometric titrations of complexes 1 and 3 have been carried out in 3:2 acetonitrile-water as a function of pH over the range 3.5-12.0 and the pK values have been determined. The kinetic parameters for the decay of the ³MLCT excited states of 1 at different pH at 298 K have been evaluated.     

The thermodynamics of the complexation of lanthanides by 1-hydroxy-4,7-disulfo-2-naphthoic acid

The thermodynamic parameters, log β, ΔH and ΔS, for formation of lanthanide-1-hydroxy-4,7- disulfo-2-naphthoic acid complexes have been determined at 25 °C in 0.10 M NaClO₄ solutions by potentiometric and calorimetric titrations. Under the experimental conditions, the data can be explained with the formation of LnL⁻, LnL₂⁵⁻ and LnHL complexes (H₂L²⁻ = 1-hydroxy-4,7-disulfo-2- naphthoic acid anion). At pH < 3 the LnHL complex is the major species, whereas by increasing pH the formation of LnL_n³⁻⁴ⁿ complexes becomes more important. The data are compared to the comparable data for complexing by aromatic carboxylic acids.     

Mono- and dinuclear (o-thioetherphenolato)-copper(II) complexes. Structural models for galactose oxidase

Three new o-thioetherphenol ligands have been synthesized: 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)ethane (H₂bse), 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)benzene (H₂bsb), and 4,6-di-tert-butyl-2-phenylsulfanylphenol (Hpsp). Their complexes with copper(II) were prepared and investigated by UV-Vis-, EPR-spectroscopy; their electro- and magnetochemistry have also been studied: [Cu^II(psp)₂] (1), [Cu^II₂(bse)₂] (2), [Cu^II₂(bsb)₂] (3), [Cu^II(bsb)(py)₂] (4). The crystal structures of the ligands H₂bse, H₂bsb, Hpsp and of the complexes 1, 2, 3, 4 have been determined by X-ray crystallography.     

Silver(I)-organophosphane complexes of the dihydridobis(3-nitro-1,2,4-triazolyl)borate ligand. X-ray crystal structure of {[H2B(tz)2]Ag[P(m-tolyl)3]2} with the scorpionate ligand co-ordinated in an unidentate κ-N fashion

New silver(I) complexes have been synthesised from the reaction of AgNO₃, monodentate PR₃ (PR₃ = P(o-tolyl)₃, P(m-tolyl)₃, P(p-tolyl)₃, P(p-C₆H₄F), SeP(C₆H₅)₃) or bidentate tertiary (dppe = bis(diphenylphosphane)ethane, dppf = 1,1′-bis(diphenylphosphane)ferrocene) phosphanes and potassium dihydrobis(3-nitro-1,2,4-triazolyl)borate, K[H₂B(tz^NO2)₂]. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H and ³¹P) NMR spectral data. The adduct {[H₂B(tz^NO2)₂]Ag[P(m-tolyl)₃]₂} has been characterized by single crystal X-ray studies. In the former, the H₂B(tz^NO2)₂ acts as a monodentate ligand utilizing the coordinating capability of only one of the additional (exo-) ring nitrogens to complete the coordination array about the silver atom.     

Synthesis, crystalline structure and photoluminescence investigations of the new trivalent rare earth complexes (Sm, Eu and Tb) containing 2-thiophenecarboxylate as sensitizer

New complexes with the general formula [RE(TPC)₃ · (H₂O)₂], where RE=Eu³⁺, Sm³⁺, Gd³⁺, Tb³⁺ and TPC=2-thiophenecarboxylate, have been prepared and investigated by photoluminescence spectroscopy. These compounds were characterized by complexometric titration, elemental analyses and infrared spectroscopy. The X-ray crystal structure has been determined for the [Eu(TPC)₃ · (H₂O)₂] compound, indicating that this complex is in dimeric form bridged by two carboxylate ions with monoclinic crystal system and space group P2₁/n. The coordination polyhedron can be described as a distorted square antiprism, where six oxygen atoms belong to the TPC ligand and two oxygen atoms belong to the water molecules, with site symmetry close to C_2v. The theoretical value of the intensity parameter , which is in agreement with the experimental one, indicates that the Eu³⁺ ion is in a highly polarizable chemical environment. Based on the luminescence spectra, the energy transfer from the ligand triplet state (T) of TPC to the excited levels of the Eu³⁺ ion is discussed. The emission quantum efficiency of the ⁵D₀ emitting level of the Eu³⁺ ion was also determined. In the case of the Tb³⁺ ion, the photoluminescence data show the high emission intensity of the characteristic transitions ⁵D₄ → ⁷F_J (J=0-6), indicating that the TPC ligand is a good sensitizer. It is also noticed that the complexes with the Eu³⁺ and Tb³⁺ ions are more luminescent than the complex with the Sm³⁺ ion.     

3,5-diacetyl-1,2,4-triazol bis(4N-substituted thiosemicarbazone) palladium(II) complexes: synthesis, structure, antiproliferative activity and low toxicity on normal kidney cells

Treatment of ⁴N-monosubstituted bis(thiosemicarbazone) ligands of 3,5-diacetyl-1,2,4-triazol series with lithium tetrachloridopalladate gave the dinuclear complexes of general formula [Pd(μ-H₃L^1-5)]₂, but using dichloridobistriphenylphosphinepalladium(II) salt, the first mononuclear bis(thiosemicarbazone)-palladium-triphenylphosphine complexes of the 3,5-diacetyl-1,2,4-triazol series, [Pd(H₃L^1-5)PPh₃], have been obtained. All the compounds have been characterized by elemental analysis and by IR and NMR spectroscopy, and the crystal and molecular structures of dinuclear complexes [Pd(μ-H₃L³)]₂ and [Pd(μ-H₃L⁵)]₂ as well as mononuclear complexes [Pd(H₃L¹)PPh₃], [Pd(H₃L²)PPh₃], [Pd(H₃L³)PPh₃] and [Pd(H₃L⁴)PPh₃] have been determined by X-ray crystallography. The new compounds synthesized have been evaluated for antiproliferative activity in vitro against NCI-H460, A2780 and A2780cisR human cancer cell lines. Subsequent toxicity study, on normal renal LLC-PK1 cells, shows that all compounds investigated exhibit very low toxicity on kidney cells with respect to cisplatin.     

Cyclic and acyclic compartmental Schiff bases, their reduced analogues and related mononuclear and heterodinuclear complexes

[1+1] macrocyclic and [1+2] macroacyclic compartmental ligands (H₂L), containing one N₂O₂, N₃O₂, N₂O₃, N₄O₂ or O₂N₂O₂ Schiff base site and one O₂O_n (n=3, 4) crown-ether like site, have been prepared by self-condensation of the appropriate formyl- and amine precursors. The template procedure in the presence of sodium ion afforded Na₂(L) or Na(HL) · nH₂O. When reacted with the appropriate transition metal acetate hydrate, H₂L form M(L) · nH₂O, M(HL)(CH₃COO) · nH₂O, M(H₂L)(X)₂ · nH₂O (M=Cu²⁺, Co²⁺, Ni²⁺; X=CH₃COO⁻, Cl⁻) or Mn(L)(CH₃COO) · nH₂O according to the experimental conditions used. The same complexes have been prepared by condensation of the appropriate precursors in the presence of the desired metal ion. The Schiff bases H₂L have been reduced by NaBH₄ to the related polyamine derivatives H₂R, which form, when reacted with the appropriate metal ions, M(H₂R)(X)₂ (M= Co²⁺, Ni²⁺; X=CH₃COO⁻, Cl⁻), Cu(R) · nH₂O and Mn(R)(CH₃COO) · nH₂O. The prepared ligands and related complexes have been characterized by IR, NMR and mass spectrometry. The [1+1] cyclic nature of the macrocyclic polyamine systems and the site occupancy of sodium ion have been ascertained, at least for the sodium (I) complex with the macrocyclic ligand containing one N₃O₂ Schiff base and one O₂O₃ crown-ether like coordination chamber, by an X-ray structural determination. In this complex the asymmetric unit consists of one cyclic molecule of the ligand coordinated to a sodium ion by the five oxygen atoms of the ligand. The coordination geometry of the sodium ion can be described as a pentagonal pyramid with the metal ion occupying the vertex. In the mononuclear complexes with H₂L or H₂R the transition metal ion invariantly occupies the Schiff base site; the sodium ion, on the contrary, prefers the crown-ether like site. Accordingly, the heterodinuclear complexes [MNa(L)(CH₃COO)_x] (M=Cu²⁺, Co²⁺, Ni², x=1; M=Mn³⁺, x=2) have been synthesised by reacting the appropriate formyl and amine precursors in the presence of M(CH₃COO)_n · nH₂O and NaOH in a 1:1:1:2 molar ratio. The reaction of the mononuclear transition metal complexes with Na(CH₃COO) · nH₂O gives rise to the same heterodinuclear complexes. Similarly [MNa(R)(CH₃COO)_x] have been prepared by reaction of the appropriate polyamine ligand H₂R with the desired metal acetate hydrate and NaOH in 1:1:2 molar ratio.     

New chiral macrocyclic lanthanide complexes derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformylpyridine

The new enantiopure complexes [LnL](NO₃)₃ · nH₂O (Ln = Dy⁺³, Ho⁺³, Er⁺³, Lu⁺³) and [LnL]Cl₃ · nH₂O (Ln = Nd⁺³, Sm⁺³, Gd⁺³, Tb⁺³, Dy⁺³, Ho⁺³, Er⁺³, Tm⁺³, Lu⁺³) of the chiral macrocycle L derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformylpyridine have been synthesised. The preference of macrocycle L for the heavier lanthanide(III) ions has been established on the basis of competition reaction. The complexes have been characterised by NMR spectroscopy and mass spectrometry. ¹H NMR signals of deuterated water solutions of the Ce⁺³, Nd⁺³ and Eu⁺³ complexes have been assigned on the basis of the COSY and HMQC spectra, and for the remaining lanthanide complexes the signals were assigned on the basis of linewidths analysis. The paramagnetic shifts of the series of lanthanide complexes [LnL](NO₃)₃ · nH₂O and [LnL]Cl₃ · nH₂O have been analysed using both crystal-field dependent and independent methods in order to separate contact and dipolar contributions and establish isostructurality along the series of lanthanide complexes in solution. The data obtained for nitrate derivatives in organic solvent indicate rather irregular deviations from the plots based on those methods, while the plots obtained for water solutions show the characteristic brake in the middle of the lanthanide series, that is interpreted as a result of change of the number of axially coordinated water molecules. The apparent inconsistencies of results obtained on the basis of crystal-field independent method are discussed.